1. Field of the Invention
This invention is related to organoclays, particularly those useful in high temperature applications.
2. Discussion of Relevant Art
Granular organoclays (organically modified clays), have found use in a variety of applications such as clean-up of ground water and wastewater. Granular organoclays are used as pre-polishers for activated carbon or as post polishers for oiltwater separators.
An organically modified clay is a bentonite or other type clay, modified with quaternary amines as outlined in U.S. Pat. No. 2,531,440 to Jordan. Certain quaternary amines consist of a paste or a solid, and will not melt until a temperature of about 175.degree. Fahrenheit is reached. The quaternary amine acts as a binder for the organoclay, if the organoclay is made by the dry method and forced through a die plate of an extruder. The quaternary is first melted, mixed with the bentonite, extruded, and upon cooling, it re-precipitates. The extrudate becomes very hard and can be granulated. When the temperature exceeds 175.degree. Fahrenheit, the quaternary amine will melt and no longer bind the clay, therefore the granules fall apart.
Various binders are used in industry for granulation. Activated carbon granules are bound by phenolic resins as disclosed in U.S. Pat. No. 5,389,325 to Bookinder. A good background of binders is found in the foundry industry. Numerous patents are mentioned in U.S. Pat. No. 4,357,165 Helferich. These include the use of alumino silicate. Other binders are magnesium chloride/magnesium oxide solutions which are rigid and become harder as time passes as disclosed in U.S. Pat. No. 3,956,900 to Klinker. Other binders are lignosulfonates (U.S. Pat. No. 4,306,912). U.S. Pat. No. 4,207,116 to Been describes binding sodium bentonite with cement and water. Gypsum and binders such as sodium silicates are also in use.